1. Field of the Invention
This invention relates to vehicle protection devices and, more particularly, to such a device for preventing the propulsion of a vehicle, even though its engine may be running.
2. Description of the Prior Art
A wide variety of theft prevention devices and systems have been developed for use with automobiles and similar type vehicles. Such devices fall generally into two separate categories: those which are designed to provide a signal, such as a siren or flashing lights, if the vehicle is being broken into; and those which are designed to prevent the engine from being started, even though the ignition switch might be bypassed. More elaborate versions of the first category may even be arranged to transmit an alarm signal to activate a remote paging device carried on the person of the owner, for example.
It is generally a relatively simple matter for a professional car thief to bypass such devices. It may take as little as fifteen seconds for such a thief to bypass an ignition system lock after entry into the automobile and such thieves usually find it a simple matter to gain entry. Many cars can be unlocked simply by expert manipulation of a coat hanger or similar implement. In such an instance, the devices of the type which provide a warning of some kind to the owner merely serve to indicate that the car is being driven away. Those devices designed to prevent the engine from being started can usually be bypassed rather readily by a professional thief, simply by the process of "hot-wiring" the ignition. The steering column lock often associated with the ignition switch can be pulled out very easily by tools which are designed for the purpose.
Vehicle protection systems of the type described can be very expensive. Prices generally start at approximately $35.00 and can run upwards of several hundreds of dollars, depending on the sophistication and complexity of the system. Moreover, installation of such systems usually requires the services of a professional installer, further increasing the cost to the owner.
The trend in recent years has been toward the inclusion of automatic transmissions in the major proportion of all new cars sold in this country. This is particularly true with respect to American-made cars and is applicable to even the high powered sport cars, such as the Corvette. In California, in fact, it has not been possible in the last few years to purchase a new automobile with engines above a certain performance rating equipped with anything other than an automatic transmission. As manufactured, many of the "sporty" type automobiles in the General Motors line utilize the same type of shift lever for the automatic transmission. This lever incorporates a hand grip on the end of a vertical shift lever extending upwardly through the floor from the automatic transmission and has a centrally positioned, thumb-operated push rod or button for disengaging the locking pawl preparatory to shifting the transmission out of the PARK position. Automobiles of the type referred to include the Corvette, the Z-28, the Trans Am, the Grand Am, the Camero, the Firebird, and the like.
Corvettes from 1964 to the current model which are equipped with automatic transmissions have the shifter grip in the form of a ball which is screwed onto the threaded end of the hollow shift lever. The ball has a vertically oriented, central bore into which the shifter post extends upwardly from the hollow shift lever. Extending from the upper end of the bore is a projecting push rod or push button which is threaded onto the shifter post. This push rod must be moved downwardly, conventionally by the driver's thumb as his right hand encircles the shifter grip, in order to shift the transmission out of the PARK position. It will be appreciated that if some means can be provided for effectively preventing the downward movement of this push rod, the transmission cannot be shifted out of the PARK position, even though the engine may be running and the automobile otherwise fully operative. Since in the PARK position the transmission (and thereby the rear wheels) are locked against turning, such a means can effectively prevent the automobile from being moved unless the rear wheels are physically raised off the ground, as by resort to a tow truck. If a tow truck is to be used in the theft of an automobile, no theft prevention system presently known can protect the automobile.
As presently manufactured, the PARK release mechanism and the ignition lock are interlocked so that the automatic transmission cannot be shifted out of PARK unless the ignition is turned on. However the interlocking mechanism is cable actuated and releases the PARK latch when the ignition lock is activated. The ease with which a car thief can bypass the ignition key lock renders this transmission locking mechanism relatively ineffectual. What is needed is a positive locking mechanism, independent of the ignition lock, which can only be controlled by a key and which cannot be disabled by a would-be thief without great difficulty and the expenditure of considerable time.